PTL 1 describes a control device for an automobile braking device and its control method. More specifically, PTL 1 describes that: (1) the control device performs arithmetic operations at a first hierarchical level, a second hierarchical level, and a third hierarchical level; (2) the result of the operation at the second hierarchical level is sent to the first hierarchical level, and the second arithmetic operation is diagnosed at the first hierarchical level based on the incoming result of the operation at the second hierarchical level; (3) when it is determined that there is any abnormality in the second arithmetic operation, the result of the operation in the first hierarchical level is sent from the first hierarchical level to the third hierarchical level, and the operation is performed in the third hierarchical level based on the result of the operation in the first hierarchical level; and (4) the braking force of the vehicle is computed in the first hierarchical level, the frictional braking force in the braking force of the vehicle is computed in the second hierarchical level, and the braking force corresponding to each wheel is computed in the third hierarchical level.